1. Field of the Invention
The present disclosure relates to a molded case circuit breaker capable of preventing insulation breakdown caused by leakage of an arc gas generated when a short circuit occurs.
2. Description of the Conventional Art
In general, a molded case circuit breaker (MCCB) is one obtained by integrally assembling an opening/closing mechanism, a trip device and the like in a container of an insulating material. The MCCB is typically a mechanism which enables an electric path in a use state to be opened/closed manually or by an electricity control device at an exterior of the insulating container, and automatically cuts off the electric path when an overload, short circuit or the like occurs.
For example, when a short circuit between lines occurs, the trip device installed in the MCCB separates a contact point, thereby cutting off the electric path. When the contact point is separated, an arc is generated, and an arc gas in a plasma state is exhausted to the exterior of the MCCB through an arc gas vent means provided in the MCCB.
FIG. 1 is a perspective view illustrating a conventional vent means for a circuit breaker according to prior U.S. Pat. No. 7,034,241. In the conventional vent means, an arc gas generated inside an interrupter assembly 70 is exhausted to a chamber area 100 through an exhaust pipe 80 at a lower end of the interrupter assembly 70. The arc gas is divided to both sides through a triangular gas division part 110 in the chamber area 100 and then exhausted to the exterior of the MCCB through a chute 90.
However, in the conventional arc gas exhaust structure according to prior U.S. Pat. No. 7,034,241, as an arc is leaked through a gap formed when a case 190 and the interrupter assembly 70 are coupled to each other, the arc is leaked to the upper end surface of the triangular gas division part 110 provided on the bottom surface of the case 190, and dust generated by the arc is absorbed on the conductor surface of a trip part, thereby forming a conduction path. Therefore, insulation between internal conductors and insulation between the internal conductor and the bottom surface (ground) of the case 190 are broken down. Accordingly, there is a problem in that an internal force with respect to a reference internal voltage of 2.2 kV is lost.